Electromagnetic tuning for efficient polarization regulation and fast polysulfide conversion of Li-S Battery

Reducing electrochemical polarization is an efficient strategy to promote electrochemical reaction and increase battery performance. Herein, we develop a magnetic tuning strategy and investigate the influence of the electromagnetic properties of NiCo2O4 on polarization and redox kinetics of Li-S battery. The electromagnetic properties of NiCo2O4 are adjusted by controlling the nanowire dimension and crystalline size, where a series of relationships between electromagnetism and polysulfide conversion reactions are established. The built-in magnetic field in ferromagnetic NiCo2O4 nanowire modulates the surface reactivity and diffusion pathway of negative species at the electrolyte/cathode interface for strong adsorption of LiPSs during cycles. The high dielectric properties of carbon cloth-supported NiCo2O4 nanowire composite (NCO-CC) improve charge carriers/ions mobility and regulate the voltage at the electrolyte/cathode interface, enhancing the electrochemical performance of the battery. The optimized NiCo2O4-CC-based Li-S battery exhibits excellent initial specific capacity (1496.1 mAh g−1 at 0.1C), high-rate capability (896.8 mAh g−1 at 1 C), and outstanding cycling stability (a decay of 0.019 %/cycle after 1200 cycles at 1 C). A high areal capacity (10.4 mAh cm−2 at 0.1C) is achieved at high sulfur loading (10.7 mg cm−2). This work provides new insights for tuning the magnetic properties of the cathode material to reduce polarization, mitigate polysulfide migration, and enhance the overall electrochemical performance of Li-S batteries.